This invention generally relates to thermal inkjet printing. More particularly, this invention relates to a printhead for a print bar and a process of manufacturing the printhead for the print bar. In particular the process includes applying, on the same side of a substrate, a fluid firing device, a fluid reservoir supplying fluid to the fluid firing device, and drive electronics supplying power and signals to the fluid firing device.
One of the more important components of an inkjet printer is the inkjet printhead. The inkjet printhead controls the application of fluid to the printing medium (e.g., paper). Typically, inkjet printheads include a plurality of fluid ejection mechanisms and control circuitry formed on first side of a silicon substrate. The silicon substrate is connected to a fluid cartridge or other fluid supply located on a second side of the substrate. Channel structures formed through a slot in the silicon substrate or above the first side of the substrate direct the fluid from the fluid supply to the firing chambers. The control circuitry supplies current to the firing resistors in selected firing chambers. The fluid within the selected chambers is super-heated by the firing resistors, causing the fluid to be ejected through the chamber orifice toward the printing medium in the form of a fluid droplet.
The fluid ejection mechanism is made of thin film layers forming resistor, and a barrier layer forming firing chambers surrounding the resistors, and an orifice plate with orifices lined up with the firing chambers. The barrier layer channels the fluid to the resistor and defines the firing chamber volume. The barrier interface material is a thick, photosensitive material that is laminated onto the substrate, exposed, developed, and cured. The orifice plate is the exit path of the firing chamber that was defined by the barrier interface. The orifice plate is typically electroformed with nickel (Ni) and then coated with gold (Au), palladium (Pd), or other precious metals for corrosion resistance. The thickness of the orifice plate and the orifice opening diameter are controlled to allow repeatable drop ejection when firing.
Silicon is a relatively expensive material when compared with other substrate materials, such as glass. Semiconductor material such as silicon is typically used in the manufacturing of the control circuitry for the resistors. However, at least a portion of the silicon is often not optimally utilized in the printhead. For example, the silicon substrate has a fluid feed slot that is formed by making a hole in the silicon substrate. The silicon that is removed is considered a waste product of the printhead manufacturing process. In addition, the resistor is applied to the silicon substrate. It is desired to more economically and efficiently utilize the silicon substrates when manufacturing printheads.
In one embodiment of the present invention, a printhead has a glass substrate with a first surface, a fluid firing device deposited on the first surface, and a fluid reservoir positioned along the first surface. The fluid firing device has a firing chamber, a heating element beneath the firing chamber, a fluid ejection orifice, and a fluid channel directing fluid to the heating element to be ejected through the orifice. The fluid reservoir is coupled with the fluid channel.
Drive electronics are applied on the first surface and electronically coupled with the fluid firing device. The drive electronics supply power and signals to the fluid firing device to eject fluid from the fluid ejection orifice. The drive electronics include a control unit and an input connector coupled with a printer.
The fluid firing device has thin film layers. The thin film layers include a conductor layer that forms conductor traces that couple with the drive electronics. The thin film layers also include a cross-linked photoimagable polymer layer that forms the fluid channel, the firing ejection nozzle, and the firing chamber.
In one embodiment, the firing chamber and the fluid ejection orifice are positioned over the heating element. In another embodiment, the fluid channel enters he firing chamber from a first side and the fluid is ejected from the firing chamber from a second side opposite the first side.
A method of manufacturing the print head includes applying a fluid firing device on a first surface of a substrate, forming a fluid channel in the fluid firing device, applying a fluid reservoir on the first surface, coupling the fluid reservoir with the fluid channel, applying drive electronics onto the first surface, and electronically coupling the drive electronics with the fluid firing device.
In one embodiment, applying the fluid firing device includes depositing a thin film stack. The thin film stack includes a cross-linking polymer having a photoimagable material, wherein forming the fluid channel includes exposing the cross-linking polymer with electromagnetic energy. In one embodiment, a multi-density level mask is positioned over the polymer while exposing the polymer.
Many of the attendant features of this invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts throughout.